User interface devices enable users to interact with and control computing-based devices. One type of user interface utilizes touch input from a user's fingers to interact with the computer. For example, a touch-pad (also called a track-pad) is commonly provided on a notebook computer, such that, by drawing their finger over the touch-pad the user can control the position of a cursor on a display. Such touch-pads can determine the position of the user's finger by detecting localized capacitance changes when a finger (acting as a virtual ground) is brought into contact with the touch-pad.
Touch-based user interfaces (such as a touch-pad) generally provide a hard, continuous surface with which the user interacts to provide input to the computer. Such devices are only able to sense the location of the user's touch on the surface of the user interface, and are not able to sense any information in other spatial directions. In addition, user interface devices which use capacitive sensing require the presence of a finger acting as a virtual ground to operate, and do not operate if the user is, for example, wearing gloves or using an implement such as a stylus. Furthermore, the user of such a touch-based user interface does not feel any physical or haptic feedback, resulting in a disconnection from the process of interacting with the computer.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known user interface devices.